Yield and Water Productivity of Drip-Irrigated Potato under Different Nitrogen Levels and Irrigation Regime with Saline Water in Arid Tunisia

Abstract

Field studies were conducted on a sandy soil during autumn of 2010 and 2011 in an arid region of Tunisia to investigate the effects of nitrogen and irrigation regimes with saline water on yield and water productivity (WP) of potato (Solanum tuberosum L. cv. Spunta) and soil salinity. For the two years, irrigation treatments consisted in water replacements of cumulated crop evapotranspiration (ETc) at levels of 100% (I100, full irrigation), 60% (I60) and 30% (I30), when the readily available water in I100 treatment was depleted, while the nitrogen treatments (N) were 0, 100, 200, and 300 kg/ha (No, N100, N200, and N300). Results showed that soil salinity values remained lower than those of electrical conductivity of irrigation water (ECiw) and were the lowest under treatment I100 and the highest with I30 treatment. Relatively low ECe values were also observed under I60 treatment. The highest potato yields for the two years were obtained with I100 treatment. Compared to I100, significant reductions in potato yields were observed under I60 and I30 deficit irrigation treatments resulting from a reduction in tubers number/m² and tuber weight. The water productivity (WP) was found to significantly vary among treatments, where the highest and the lowest values were observed for I30 and I100 treatments, respectively. Potato yield and WP increased with an increase in nitrogen rates. The rate of 300 kg N/ha was seen to give good yield and higher WP of potato under full (I100) and deficit (I60) irrigation treatments. However, application of N adversely affected potato yield and WP, when N level applied above 200 kg N/ha at I30. The WP was improved by N supply, but its effect decreased as the irrigation level increased. The IWP at I100, which produced the highest potato yield, was 8.5 and 9.9 kg/m 3 with N300 but this increased to 11.9 and 15.6 kg/m 3 at I30 with N200, in 2010 and 2011, respectively. These re-* Corresponding author.F. El Mokh et al. 502sults suggested that potato in arid region could be cultivated with acceptable yields while saving irrigation water and reducing nitrogen supply but it was essential to exploit the interaction effect between these two parameters to maximize resource use efficiency.

Effect of soil and water characteristics on yield and properties of ‘Spunta’ potatoes

“…In addition, findings by Abdullah and Ahmed (1990) indicated that tuber number per plant increased with low salinity concentration and decreased with increasing salinity concentration. Moreover, potato tuber yield varied widely under different amounts of water, applied with different EC of water through drip irrigation at different levels (El Mokh et al, 2015). In this study, the lowest yield was 34.12 t ha -1 at a SWQI 79.63% and the highest yield was 37.79 t ha -1 at a SWQI 30.93%.…”

“…Van Hoorn et al (2002) grew potatoes in tanks filled with loam and clay and irrigated with water of three different levels of salinity; water efficiency of potatoes was not affected by soil and water salinity. El Mokh et al (2015) showed that potato tuber yield varied widely under different amounts of water that was applied with different EC through drip irrigation at different levels. A higher salinity associated with deficit irrigation caused significant reductions in tuber yield and its components.…”

Interaction Effects of Nitrogen Source and Irrigation Regime on Tuber Quality, Yield, and Water Use Efficiency of Solanum tuberosum L.

“…Iernaa and Mauromicale [8] applied deficient irrigation and increased water productivity. El-Mokh et al [6] obtained the highest yield under supplementary irrigation, while Bélanger et al [13] found that irrigation increased the weight per tuber.…”

“…In addition, Badr et al [20] stated that the full irrigation of potato resulted in the highest tuber yield with different investigated N levels used in their study, while a significant decrease in the tubers yield occurred in plants irrigated with low amounts of irrigation water. Moreover, El-Mokh et al [6] reported that irrigation with 100% ETc + 300 kg N ha −1 resulted in the highest potato tuber yield. However, Yuan et al [10] and Onder et al [54] reported a significant reduction in the tuber yield with decreasing levels of applied water.…”

“…The excessive inputs in agricultural systems that can achieve high productivity and quality of crops to feed a growing population are considered to be some of the most troublesome agricultural practices for environmental resources [5][6][7]. Thus, increasing food crop cultivation requires the rationalization of the inputs such as water and fertilizer applications.…”